Dynamoelectric machine



1943- c. A. THOMAS DYNAMOELECTRIC MACHINE Filed Sept. 28, 1946 Char'fiesAThmmas, v y

Patented Nov. 23, 1948 DYNAMOELECTRIC MACHINE Charles A. Thomas, FortWayne, Ind., assignor to General Electric Company, a corporation of NewYork Application September 28, 1946, Serial N0. 700,152

Claims.

My invention relates to dynamoelectric machines and particularly to anarrangement for improving the sensitivity and speed of response of anarmature reaction excited dynamoelectric machine.

An object of my invention is to provide an improved armature reactionexcited dynamoelectric machine.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

The drawing schematically illustrates in Fig. 1 an armature reactionexcited dynamoelectric machine provided with an embodiment of myinvention for increasing the sensitivity and speed of response thereoi;and Fig. 2 schematically A shows another embodiment of my invention.

Referring to the drawing, I have shown in Fig. 1 a dynamoelectricmachine of the armature reaction excited type which includes a rotatablemember or armature i having a commutator with a conventional windingconnected thereto and a set of commutator primary brushes 2 and 3 and aset of commutator secondary brushes 4 and 5 displaced about thecommutator substantially 90 electrical degrees from the primary brushset. The primary brushes 2 and 3 are connected together in theillustrated machine by a shortcircuiting shunt conductor 6 to provide aprimary or short circuit through the armature. As in a conventionalmachine of this type, a control field exciting winding 1 is providedwhich may be energized by any suitable source of electrical power supplyconnected across its terminals to provide energizing current theretowhich may a be controlled by any suitable arrangement, such as avariable resistor 8.

In this type machine, the control field exciting winding 1 induces avoltage between the primary brushes 2 and 3, such that a primary orshort-circuit current flows through the armature primary circuit whichprovides a primary component of armature reaction indicated by an arrow9. This component of armature reaction induces a voltage between thesecondary brushes 4 and 5 which will cause a current to flow through thesecondary circuit of the armature when a load is connected to thesebrushes. This flow of current through the armature secondary circuitwill produce a secondary component of armature reaction as indicated bythe arrow [0 in opposition to the control component of excitationindicated by the arrow ii. In order to minimize the eflect of secondaryarmature reaction on the control of the machine, a compensating fieldexciting winding I2 is provided which is energized in response to thesecondary current of the machine by being connected in series with thesecondary brush 4. This compensating field exciting winding i2 isadapted-to produce a component of excitation along the secondarycommutating axis of the machine as' indicated by the arrow 43 inopposition to the secondary component of armature reaction l0, so assubstantially to neutralize the secondary armature reaction. In thisarrangement, the terminal of the compensating field exciting winding l2and the other terminal of the machine connected to the secondary brush 5are adapted to be connected to any suitable load through conductors H.

The sensitivity and speed of response of the machine are adapted to begreatly increased by the provision of an auxiliary control fieldexciting winding l5 which is energized in response to the secondaryvoltage 01. the machine to provide a component of excitation, indicatedby the arrow i6, cumulative to that of the control field excitingwinding 1 along the secondary commutating axis or the machine. Thisenergization of the winding i5 is obtained by connecting it across theterminal of the secondary brush 5 and the terminal of the compensatingfield exciting winding l2 through a nonlinear negativevoltage-resistance characteristic resistor ii. A resistor of i this typehas the characteristic that when placed in circuit with a source ofelectric potential its resistance falls with an increase of potential inthe circuit, the change of resistance being independent of temperaturechange. Such a resistor is described in Patent 1,822,742, McEachron,assigned to the assignee of the present application, and is commonlyreferred to as a Thyrite resistance. The resistor i1 is adaptedinherently to vary the energization of the auxiliary control fieldexciting winding i5 nonlinearly for providing relatively largeincrements of changes of excitation with changes the secondary or outputvoltage of the machine. This inherent nonlinear variation of theresistance of the circuit of the auxiliary control field excitingwinding IS in the same sense as variations in the secondary voltage ofthemachine is such that as the voltage of the machine is increased byincreased excitation provided by the main separately excited controlfield exciting winding I, the total control excitation of .e machine isgreatly increased by the excitorovided by the cumulative auxiliary fieldwinding vhercas when the voltage eases, the efiecti resistance of theThyrite rtor iii greatly increases until at low voltages or ct residualvoltage or" the machine, the excitatio provided by uuxiliery fieldexciting L i5 is very small. is slight reversal of the energizotion ofmain control field excitinc; winding i may be used to reduce thesecondary or output voltage or the machine substentially to zero. Inthis manner, the response of the machine is greatly increased and thesensitivity thereof also is increased.

in Fig. 2, I have shown another embodiment of my invention applied to edynamoelectrlc machine of the armature reaction excited type pros videdwith a rotatable member or armature l similar to that of Fig. l andother corresponding parts to which reference numerals have been givencorresponding to the same numbered parts in Fig. 1. The armature i isprovided with a commutator connected to a conventional armature winding,and a set of primary commutator brushes 2 and 3 are arranged in contactwith the commutator and substantially short circuited in the illustratedarrangement by a conductor 3 to provide a primary or short circuitthrough the armature. A set of secondary brushes l and 5 is provided andis displaced about the commutator substantially 90 electrical degreesfrom the primary brush set and adapted to be connected to any suitableload circuit through terminal leads I l. As in a conventional machine ofthis type, a, control field exciting winding l is provided which may beenergized by any suitable source of electrical power supply connectedacross the terminals to provide energizing current thereto which may beregulated in any desirable manner, as by a variable resistor 8.

With such an arrangement, the control field exciting winding 1 isadapted to induce a voltage between the short circuit primary brushes 2and 3 such that a. primary current flows through the armature primarywinding and provides a. pri mary component of armature reaction, asindicated by the arrow 9. This component of armature reaction induces avoltage between the secondary brushes 4 and 5 which will cause atcurrent to flow through the secondary circuit ofthe armature when it isconnected to a load through the leads it. This flow of current throughthe armature secondary circuit produces a secondary component ofarmature reaction, as indicated by the arrow in, in opposition to thecontrol component of excitation indicated by the arrow I l and providedby the field exciting windlng F. In order to minimize the effect ofsecondary armature reaction on the control of the machine, acompensating field exciting winding 32 is provided which is energized inresponse to the secondary current of the machine by being connected inseries with the secondary brush t. This compensating field excitingwinding i2 is adapted to produce a component of excitation,

indicated by the arrow E3, in opposition to the secondary component ofarmature reaction it so as substantially to neutralize the efiect ofthis secondary armature reaction.

The sensitivity and speed of response of the machine may be increased bythe provision of an auxiliary control field exciting winding iii whichis energized in response to the secondary voltage of the machine toprovide a component of excitation, indicated by the arrow is, cumu-33-53% m th primary armature reaction 9 along the primary commutatingaxis of machine for inducing a cumulative component of voltage to thatresulting from the excitation provided by the main control fieldexciting winding 3. Thls auxiliary held exciting winding is adapted toenergized through a nonlinear negative voltsge-resistance characteristicresistor such as a Thyrite resistance, connected directly across thesecondary or'load terminals or the machine. The nonlinear resistor isadapted inherently to vary the energization of the auxiliary controlfield exciting winding ill in amanncr similar to that explained withrespect to the field exciting winding it and the resistor ill in Fig. 1so as to increase the sensitivity and the speed of response of themachine to variations of the excitation provided by the main controlfield exciting winding 1.

While I have illustrated and described a partlcular embodiment of myinvention, modificatlons thereof will occur to those skilled in the art.I desire it to be understood, therefore, that my invention is not to belimited to the particular arrangement disclosed, and I intend in theappended claims to cover all modifications which do not depart from thespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A dynamoelectrlc machine having an arms.- ture with a commutator anda winding connected thereto, means including o commutator primary brushset and a, commutator secondary brush set for respectively providing aprimary circuit and a secondary circuit through said armature winding, afield exciting winding arranged to provide a component of excitationalong the secondary commutating axis of said armature, means ineluding asecond field exciting winding for substantially neutralizing armaturereaction due to current in said armature secondary circuit, meansincluding a third field exciting winding for providing a component ofexcitation along the primary commutating axis of said machine cumulativeto armature reaction due to current in said armature primary circuit andarranged to be energized in response to the voltage of said secondarycircuit, and means including a nonlinear negative voltage-resistancecharacteristic resistance connected in series with said third fieldexciting winding.

2. A dynamoelectric machine having an arms.- ture with a commutator anda winding connected thereto, means including a commutator primary brushset and a commutator secondary brush set for respectively providing a.primary circuit and a secondary circuit through said armature winding, afield exciting winding arranged to provide a component oi excitationalong the secondary commutating axis of said armature, means including asecond field exciting winding for substantially neutralizing armaturereaction due to current in said armature secondary circuit, meansincluding a third field exciting winding for proriding a component ofexcitation along the secondary commutatlng axis of said machinecumulative to said first-mentioned field exciting winding and arrangedto be energized in response to the voltage of said secondary circuit,and means including a nonlinear negative voltage-resistancecharacteristic resistance connected in series with said third fieldexciting winding.

3. A dynamoelectric machine having an armature with a commutator and awinding connected thereto, means including a commutator primary brushset and a. commutator secondary brush set for respectively providing aprimary circuit an a secondary circuit through said armature winding, afield exciting winding arranged to provide a, component of excitationalong the secondary commutating axis of said armature, means including asecond field exciting winding for opposing armature reaction due tocurrent in said armature secondary circuit, means including a thirdfield exciting winding for providing a component of excitation along thesecondary commutating axis of said machine cumulative to saidfirst-mentioned field exciting winding and arranged to be energized inresponse to the voltage of said secondary circuit, and means including anegative voltage-resistance characteristic resistance connected inseries with said third field exciting winding for providing relativelylarge increments of change in excitation with changes in secondaryvoltage of said machine.

i. A dynamoelectric machine having an armature with a commutator and awinding connected thereto, means including a commutator primary brushset and a commutator secondary brush set {or respectively providing aprimary circuit and a secondary circuit through said armature winding, afield exciting winding arranged to provide a component of excitationalong the secondary coinmutating of said armature, means including asecond field exciting winding for opposing armature reaction due tocurrent in said armature secondary circuit, means including a thirdfield exciting winding for providing a component of excitation along thesecondary commutating axis of said machine cumulative to saidfirst-mentioned field exciting winding and arranged to be energized inresponse to the secondary voltage of said machine, and means including anonlinear negative voltage-resistance characteristic resistanceconnected in series with said third field exciting winding inherentlyvarying the energization thereof nonlinearly for providing relativelylarge increments of change in excitation with changes in voltage of saidmachine.

5. A dynamoelectric machine having a rotatable member with a winding anda commutator connected thereto, a set of primary brushes and a set ofsecondary brushes displaced about said commutator from said primarybrushes for providing a primary circuit and a secondary circuitrespectively through said rotatable member winding, a field excitingwinding arranged to provide a component of excitation along thesecondary commutating axis of said machine, means including a secondfield exciting winding for providing a component of excitation along thesecondary commutating axis of said machine for substantiallyneutralizing the secondary armature reaction of said machine, meansincluding a third field exciting winding for providing a component ofexcitation along the secondary commutating axis of said machinecumulative to said first-mentioned field exciting winding and arrangedto be energized in response to the voltage of said secondary circuit,and means for inherently and nonlinearly varying the resistance of thecircuit of said third field exciting winding in the same sense asvariations in the secondary voltage of said machine.

6. A dynamoelectric machine having a rotatable member with a winding anda commutator connected thereto, a set of primary brushes and a set ofsecondary brushes displaced about said commutator from said primarybrushes for providing a primary circuit and a secondary circuitrespectively through said rotatable member winding, a field excitingwinding arranged to provide a component of excitation along thesecondary commutating axis of said machine, means including a secondfield exciting Winding for providing a component of excitation along thesecondary commutating axis of said machine for substantiallyneutralizing the secondary armature reaction of said machine, meansincluding a third field exciting winding for providing a component ofexcitation along the secondary commutating axis of said machinecumulative to said first-mentioned field exciting winding and adapted tobe energized in response to the voltage of said secondary circuit, andmeans for nonlinearly varying the resistance of the circuit of saidthird field exciting winding for larger changes in resistance withlarger variations in the secondary voltage of said machine.

7. A dynamoelectric machine having a rotatable member with a Winding anda commutator connected thereto, a set of primary brushes and a set ofsecondary brushes displaced about said commutator from said primarybrushes for providing a primary circuit and a secondary circuitrespectively through said rotatable member winding, a field excitingwinding arranged to provide a component of excitation along thesecondary commutating axis of said machine, means including a secondfield exciting winding for providing a component of excitation along thesecondary commutating axis of said machine in opposition to thesecondary armature reaction of said machine, means including a thirdfield exciting winding for providing a component of excitation along thesecondary commutating axis of said machine cumulative to saidfirst-mentioned field exciting winding and arranged to be energized inresponse to the secondary voltage of said machine, and means including anonlinear negative voltageresistance characteristic resistance connectedin series with said third field exciting winding inherently varying theenergization thereof nonlinearly for providing relatively largeincrements of change in excitation with changes in voltage I of saidmachine.

- commutating axis of said machine, means ineluding a second fieldexciting winding for providing a component of excitation along thesecondary commutating axis of said machine for substantiallyneutralizing the secondary armature reaction of said machine, meansincluding a third field exciting winding for providing a component ofexcitation along the secondary commutating axis of said machinecumulative to said first-mentioned field exciting winding and arrangedto be energized in response to the voltage of said secondary circuit,and means for varying the resistance of the circuit of said third fieldexciting winding in the same sense as variations in the secondaryvoltage of said machine.

9. A dynamoelectric machine having an armature with a commutator and awinding connected thereto, means including a. commutator primary seesawbrush set, and e commufictor secondary brush sci;

, for respectively providing a primary circuit and;

a secondary circuit through seicl armature winding, a field excitingWinding errengeci to provide a component of excitation clone thesecondary commutating axis of said armature, means in cluding a secondfield exciting winding for op posing arms-sure reaction due to currentin said armature secondary circuit, meems including a third fieldexciting winding for providing a, co )2. ponent of excitetion clone theprimary commu= lasing axis of said machine for inducing e cumu= letivecomponent of voltage to that resulting from said first=mentioned fieldexciting winding excitation and arranged to be energized in response tothe voltage of said secondary circuit, and means including a negativevoltage-resistsame characteristic resistance connected in series withsaid third field excltln winding for p-lfovifiins relatively lergeincrements of change in excel tecicn with changes in secondery voltageof said machine.

lo. dvnemoelecsric machine having a 2'0- seteble member with awindingand: col totes connected thereto, a, set of priz" ry L s setoiseccnclery brushes dis said ccmmutatoi from seicl primary Mush prcvidinge primary circuit; and. 8 seconds cull", respectively through selclrotsfieble winding, 9, field exciting Wmiing serene whereby shez'espcnse and, sensitivity of W oncle-ry commute'cing axis of soldmachine, mesns including e secoczol field exciting winding for providinge compcszent of exciteision along the sec= oncleryeommcficting axis ofsaid. machine lcr sucstanlislly neutralizing the secondary oil-me turereaction of said machine, means including e third field exciting windingfor providing component of excitation to seicl machine for inducing acumulative component of voltage to that resulting from said firstmenfiioned field ez-s' citing winding excitation and arranged to leeenergz'zeo. in l'esponse to she voltege of selcl sec" ondery cicc'altend meens including 9, nonlinear negative rolfc-ege-iesistancecherecfierislle Ere sisfience connected in series with said third, fieldexciting Winciing for inherently and nonlin erlgr "he resistance ofcircuit of said I finding in the some sense as varie tiers in. thesecondary voltage c1 said mach? nsmoelectrie machine is increased.

" Mun..- Nov.

